Motorcycles exhibit handling characteristics which are superior in many ways over automobiles, and have less aerodynamic drag and reduced rolling resistance as compared with standard automobiles and automobile tires. Reduced aerodynamic and rolling resistance result in improved fuel economy and vehicle performance. The preferred embodiment of the invention has four tires and is therefore capable of carrying a higher gross weight than a typical motorcycle with two tires. The vehicle can accommodate a larger and heavier engine, heavier fuels and loads such as batteries, more cargo, and the weight of an enclosed aerodynamic body to protect the occupants from the elements and from crashes, while reducing aerodynamic drag.
A vehicle designed around this concept can be constructed as narrow as a motorcycle, which is important because frontal area and shape are significant determinates of aerodynamic drag. The combination of minimal frontal area, an enclosed aerodynamic passenger/cargo compartment, and low rolling friction (drag) motorcycle tires yields improved fuel economy.
Such a vehicle would not require computers, sensors, or mechanical systems to lean the vehicle or to keep it upright at speed. The only lean control mechanism required is a simple combination of bracing which will lock the vehicle in an upright position when parked or at slow speeds, such as when backing or otherwise maneuvering with feet on the ground.
The vehicle's suspension system can be softer and provide a smoother ride than motorcycles and many non-tilting vehicles such as autos, trucks, and ATVs. Typical motorcycle suspension systems are thirty to fifty percent stiffer than those of non-tilting vehicles because motorcycles experience all of the lateral acceleration or “G” force loading occurring during turning maneuvers. The proposed suspension system experiences none of the lateral acceleration of a motorcycle because the suspension system does not lean while turning. It remains in and acts only in the vertical like the suspension system of a typical non-leaning vehicle. Suspension systems of non-tilting vehicles must resist the forces causing the vehicle to lean to the outside of a turn and the resulting outward weight transfer. The proposed suspension system experiences no lateral weight transfer while turning because the vehicle's center of mass is moved to the inside of the turn similar to that of a motorcycle during a balanced turn.
Compared with a typical two-wheeled motorcycle, the preferred embodiment will have twice the traction, thereby promoting shorter braking distances, improved cornering, and the ability to accommodate more powerful engines. Due to the relatively smaller contact patch of motorcycles, the vehicle is less susceptible to hydroplaning than automobiles and trucks. Having the same overall width of a motorcycle makes a vehicle easier to maneuver, requires less parking space, and has access to car pool lanes.
With two front wheels, this design has inherently better front wheel traction, is more stable, and safer than vehicles with one tilting or fixed front wheel. As weight shifts forward as a vehicle slows and stops, front wheel traction is critical for stopping quickly, thus providing a major safety factor.
The prior art is replete with three-wheel tilting chassis. Two exemplary references are U.S. Patent Application 2007/0176384 to Brudeli and U.S. Patent Application 2006/0255550 to Pfeil. In both of these cases, which are typical of the genre, the drive system tilts with the rear, or driven, wheel. Such a tilt of the drive system, however, would not be compatible with an engine and drive train connected to driven wheels through a differential, as might be desirable for the reasons discussed above. If the differential were to be tiltable, the rotation of the drive shaft would bias the tilt attitude while creating complex angles with the driven axles.
Other references, such as U.S. Patent Application 2008/0238005 to James, disclose feedback mechanical systems to control lean. This may be an over-complication, however, considering the case of a motorcycle where no control other than that provided by the rider is needed. A motorcyclist, when provided with handlebar steering, will have a sense of balance while leaning and will know to counter-steer in order to initiate a turn.
U.S. Patent Application 2008/0197597 to Moulene discloses a four-wheel tilting chassis. All components of Moulene's chassis, however, also tilt. Moulene does not disclose sufficient detail of the drive mechanism to understand how it would operate in the context of a tilt.
What is missing in the prior art is a non-tilting component to a tilting chassis structure whereby a power transmission system comparable to an automobile is enabled for the benefits of the same combined with those of a motorcycle.